Vertical hydraulic presses for forming ceramic tiles are taught in the prior art, and usually exhibit a structure or frame which connects mobile and fixed parts of the press, which structure has to be very rigid and, in the example, is typically a closed frame with two uprights; access to the work area being afforded by two work benches, fore and aft of the frame.
There is usually a very large free space (indeed, as large as possible) between the two uprights or columns (which define the “mouth” of the press, through which the material to be formed enters). This free space is modelled on the basis of the largest tile format to be used (rectangular), as this is largest flat surface that will have to be modelled in the press through necessarily intermittent and discontinuous operations.
The fact of having a large area for introduction of material, combined with a much smaller depth, is connected with the need to minimise the run of a usual material loading truck, with the aim of penalising the productivity rate as little as possible.
A consequence of this necessarily large opening between the uprights is that the rigid structure of the press develops in a perpendicular plane to the plane of entry of the material to be formed, and is rather massive and tall—so tall in fact that in some cases the press has to be partially interred to give the necessary stability to the structure.
The height of these structures is basically due to the usual constructional technique which includes the use of a base and an upper crossbar, connected by the uprights, which have to be very thick in a vertical direction in order to confer a high degree of undeformability to the two planes bearing the brunt of the reactions following the pressing action. These two planes are those on which the upper and lower parts of the mould operate.
By way of example, in hydraulic presses used for forming ceramic tiles, which presses are liable to exert a pressing force of up to 7,000 tonnes and which have a free space between the uprights of more than 2 meters, the whole structure can be above 7 meters high, and can be buried by up to a third.
In consideration of the forces in play, in order to guarantee these known structures sufficient undeformability so that they can cope with any possible defects in power loading in the moulds, various solutions have been proposed, including constructionally complex ones which are not entirely satisfactory.
The same applicant provided interesting technical solutions, object of EP publications EP 1008438 and EP 1118456. These solutions, while able to resolve the main problems of the prior art as outlined herein above, have a certain constructional complexity, namely the manufacture of a considerable number of parts, and assembly thereof which is neither easy nor smooth.
Further, the coupling of mobile segments 3 on the single arches which modularly assembled form the press, which mobile segments 3 are half-moon shaped and located opposite one another, and between which the hydraulic actuator operates, can represent a drawback from the functional point of view (as well as others) inasmuch a certain degree of maintenance is required.
The main aim of the present invention is to obviate the limitations in the prior art by providing a compact, light and simply-constructed press.
A further aim of the invention is to provide a press structured modularly, with which it is both possible and simple, without changing the inlet “mouth”, to vary the maximum pressing force attainable.
An advantage of the invention consists in the fact that it exhibits a structure which, compared in terms of maximum force attainable with other presses, is notably light and small.
A further advantage of the invention is that it is constructionally very simple, in particular as regards the number of separate parts and the assembly techniques of those parts.
A further advantage is that the press is compact, making transport thereof easier as well as installation at destination.
A still further advantage is that the press can be used in a plant for forming ceramic tiles by powder press-forming, in which a continuous line operates which comprises a mobile conveyor plane supporting both the material (powders) to be pressed and the formed material ready for pressing. The conveyor “crosses” a forming device (mould) coupled to the invention itself.